This present invention generally relates to high-power-density power modules and, more specifically; to an electrically-powered, high-power-density power module useful as a power converter or inverter that can operate in an elevated temperature environment, with reduced weight and size, and increased reliability, which are critical for aircraft, space, military as well as many industrial applications.
In a completely sealed vehicle compartment, such as found on electrical aircraft and spacecraft subsystems, the ambient temperature of the power converters can be over 90 degrees centigrade, which is often dictated by use of hydraulic fluid as the coolant. However, a conventional power converter design is unable to achieve this operating temperature due to the built in thermal impedance of the power device or module and limited power device junction temperature.
IGBTs (Isolated Gate Bipolar Transistors) are popular power devices in use as pulse-width modulated power converters/inverters. However, their junction temperature is rated for operation at or below 125 degrees centigrade in accordance with FIG. 5.
The devices must be derated to zero operating power at 150 degrees centigrade. The temperature effects on power semiconductor device parameters also include increased on-resistance or on-stage forward voltage drop, increased leakage current, reduced break down voltage and reduced switching speed. These effects significantly increase total power loss, thus increasing thermal stress and cooling requirements for the power devices and decreasing the converter efficiency.
As can be seen, there is a need for a dual-side thermal interface and cooling design which effectively reduces the equivalent thermal impedance on the power module by 20% and which also reduces the temperature rise of the junction temperature of the power devices inside the power module by 20% with an equivalent load current. Such a dual-side thermal interface and cooling design reduces the weight and volume associated with conventional cooling mechanisms not employing a dual thermal interface and increases the ambient operating temperature limit of the power converter.